Thermal neutron backscatter imaging

Objects of various shapes, with some appreciable hydrogen content, were exposed to fast neutrons from a D-T generator, resulting in a partially-moderated spectrum of backscattered neutrons. The thermal component of the backscatter was used to form images of the objects by means of a coded-aperture thermal-neutron imaging system. Timing signals from the neutron generator were used to gate the detection system so as to record only events consistent with thermal neutrons traveling the distance between the target and the detector. The technique may have application in the detection and shape-determination of land mines, particularly non-metallic types.